Discussion on Hamaker Constant

Category

Published on

08 May 2008

Abstract

The Hamaker constant is a force constant used for describing the van der Waals (vdW) force. The magnitude of the Hamaker constant reflects the strength of the vdW force between two particles, or between a particle and a substrate. It depends on the material properties of both the interacting bodies and the intervening media. More accurate calculations of Hamaker constants require a knowledge of the dielectric and optical properties of the interacting materials over the entire frequency range in the electromagnetic spectrum. In general, this information s not readily accessible.

Beaudoin et. al.’s approach to determining Hamaker constants is based on the measurement of the adhesion forces (F) between two interacting bodies (e.g. particle- particle, or particle- substrate) over a range of separation distance (d). This information is measured using atom force microscopy (AFM). When the separation distance is smaller than 15nm, the vdW force is the most dominant force. The measured force curve in this region (d<15nm) is used to fit our model’s force-distance predictions in order to determine the Hamaker constant.